Nausea refers to an unpleasant sensation that is often localized to the abdomen and typically interpreted as an urge to vomit. Vomiting is the forceful oral expulsion of gastric contents. Although nausea and vomiting are the major symptoms of many gastrointestinal disorders, diseases of other organ systems should be considered during the workup. Nausea and vomiting can be due to early pregnancy, an adverse effect of medications or toxic ingestion, or a host of pathologies in other organ systems such as the CNS, endocrine, and vestibular systems. Nausea and vomiting may also be the manifesting symptoms of a functional disorder. Patients presenting with acute onset of recurrent vomiting should be evaluated for signs of dehydration and electrolyte and acid-base disorders, which should be corrected at the earliest opportunity. A thorough history and physical examination should be performed to narrow down the differential diagnoses and guide further diagnostic workup and treatment. Accompanying symptoms (e.g., fever, abdominal pain, headache) may provide clues as to the underlying disorder. Nausea and vomiting in children are not addressed here.
Evaluate and stabilize life-threatening complications before identifying and treating underlying causes of nausea and vomiting. The highest yield step to determine etiology is a thorough clinical evaluation.
Initial management 
- Consider airway protection is required (e.g., altered mental status). if
hypovolemic shock is present.
- Insert two large-bore peripheral IVs and administer IV
- If is suspected (e.g., unstable patients with coffee-ground emesis): order type and blood immediately.
- Respiratory support, e.g., oxygen therapy as needed
- Conduct a focused history and physical examination.
- Identify and treat potentially life-threatening sequela of vomiting, e.g.:
- Acid-base disorders
- Electrolyte imbalance (see “ ”)
- Administer .
- Establish NPO status in patients with intractable or recurrent vomiting for whom a life-threatening cause of nausea and vomiting has not been ruled out.
- Perform targeted diagnostics (see “Diagnostic workup of nausea and vomiting”).
- Urgent specialty consult: as needed (See also “Disposition.”)
- Supportive care: as needed
- Treating the underlying etiology: Rule out life-threatening causes first.
Many herbal supplements can result in poisoning or cause herb-drug interactions that lead to nausea and vomiting (e.g., St John's Wort may cause serotonin syndrome); ask all patients specifically whether they use any herbal supplements. 
Consider whether antiemetics are necessary: Nausea may be self-limiting, and adverse effects of antiemetics include extrapyramidal symptoms due to metoclopramide and QT prolongation due to ondansetron. 
Red flags for nausea and vomiting
The following are red flags for life-threatening causes of nausea and vomiting.
- Chest tightness
- Feeling of impending doom
Immediately life-threatening causes
- Hemorrhagic stroke
- CNS infection (e.g., meningitis, encephalitis)
- Myocardial infarction
- Acute pancreatitis
- Bowel obstruction
- Bowel perforation
- Acute mesenteric ischemia
- Diabetic ketoacidosis
- Adrenal crisis (Addison crisis)
- Drug overdose/withdrawal
- Poisoning (e.g., ingestion of toxins)
Common complications of vomiting 
- Pulmonary: aspiration pneumonitis and pneumonia
Consider hospital admission in patients with any of the following:
- Severe vomiting refractory to antiemetic therapy
- Unremitting pain
- Significant metabolic abnormalities
- Evidence of an acute underlying condition or surgical pathology that requires in-hospital evaluation and treatment
- Insufficient response to IV fluids
- Inability to adhere to discharge instructions or attend outpatient follow-up
Consider discharge home if all of the following criteria are fulfilled:
- There are no life-threatening causes identified or other criteria for admission.
- The patient appears well, can tolerate oral clear liquids, and can adhere to discharge instructions.
- Outpatient follow-up is ensured.
Not all patients require IV hydration; is effective and can be considered in patients without shock, refractory vomiting, or serious underlying pathology to reduce costs, admission rates, and complications. 
There is no standard panel of tests to determine the etiology of nausea and vomiting because of the broad differential diagnosis. Choose diagnostic testing based on clinical suspicion.
In patients with severe and sustained vomiting
- Blood gas analysis
- Urine ketones
Further diagnostic studies 
|Diagnostic testing based on suspected system involvement|
|Laboratory studies||Imaging and other interventions|
Rome IV diagnostic criteria for functional nausea and vomiting disorders 
Diagnosis of a functional nausea and vomiting syndrome requires symptom onset at least six months prior, with symptoms present for the previous three months.
Chronic nausea and vomiting syndrome (CNVS)
- Nausea at least once a week and/or one or more instances of vomiting per week
- Exclusion of self-induced vomiting, eating disorders, regurgitation, or
- Routine investigations are negative for organic, systemic, or metabolic diseases that could explain the symptoms.
- Acute episodes of vomiting, lasting less than one week
- A minimum of three episodes of vomiting in the prior year and two episodes in the past six months, with at least one symptom-free week in between the most recent episodes
- No vomiting outside of acute episodes (other milder symptoms may be present)
Life-threatening causes of nausea and vomiting
|Clinical features||Diagnostic findings||Acute management|
|Acute coronary syndrome |
|Acute pancreatitis |
|Mechanical bowel obstruction |
|Meningitis || |
|Hyperemesis gravidarum || |
Other causes of nausea and vomiting
|Clinical features||Diagnostic findings||Acute management|
|Postoperative nausea and vomiting (PONV) || || |
| || |
Uncomplicated first-trimester nausea and vomiting 
Infectious gastroenteritis 
Vestibular causes 
Nausea and vomiting are common adverse effects of numerous medications. When this occurs, use suitable alternatives or start with a lower dose to minimize symptoms.